JP2001514406A - System and method for implementing a dynamic cache in a supervisory control system - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention is directed to a system and method for controlling associated processes of a process facility, and in particular, for efficiently distributing data between nodes of a real-time process control system that controls such facilities. I will provide a. An example process control system includes a plurality of sensors, controllable devices, communication paths, and a computer system. The sensors and controllable devices are associated with various processes of the process equipment, and the communication path couples the sensors and controllable devices to a computer system. The computer system operates on data associated with the process equipment and distributes the data between the client nodes and the process nodes. The client node desires data related to the facility's process, and the process node controls such process data. The computer system includes: (i) a cache for retrieving records with a short access time; and (ii) associated with the client node and the process node, controlling storage of process data in the cache; And a supervisory controller for selectively transferring process data to the computer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to the inventions disclosed in (1) US patent application Ser. No. 08 / 920,265 and (2) US patent application Ser. No. 08 / 916,871. The application is commonly assigned to the assignee of the present invention and is filed concurrently with the present invention. The disclosures of these related patent applications are hereby incorporated by reference for all purposes as if fully set forth herein.

FIELD OF THE INVENTION [0002] The present invention relates generally to process control systems, and more particularly to a process control system using a dynamic cache database within a supervisory control system;
A method of operating the system.

BACKGROUND OF THE INVENTION [0003] Many process facilities (such as manufacturing plants, mineral or crude oil refining plants) are managed using distributed control systems. A typical state-of-the-art control system includes a number of modules tuned to monitor and / or control various processes of the facility. Conventional means link these modules and create the decentralized nature of the control system. This improves performance and provides the ability to scale up or down the control system to meet changing equipment needs.

[0004] Process equipment management providers such as Honeywell can be tailored to meet a wide range of process requirements (global, local, etc.) and equipment types (manufacturing, storage, refining, etc.). We are developing a control system. Such providers have two main purposes. The first objective is to improve the overall efficiency of the installation by focusing on controlling as many processes as possible. A second purpose is to support a common interface for communicating data between the various modules that control or monitor the process, and between the modules and the centralized controller or operator center.

Each process or group of related processes has one or more input characteristics (flow, supply, power supply, etc.) and one or more output characteristics (temperature, pressure, etc.) associated therewith. Model predictive control ("MPC") techniques have been used to optimize a given process as a function of such properties. One MPC
The technique uses an algorithmic representation of a given process to estimate property values (expressed as parameters, variables, etc.) associated with these properties that can be used to better control such processes. I'm using In recent years, physical, economic, and other factors for these related processes have also been incorporated into control systems.

An example of such a technique is “Method of Multivariable”.
Predictive Control Utilizing Range
U.S. Pat. No. 5,351,184 entitled "Control"
d of Incorporating Independent Feedf
orward Control in a Multivariable Pr
U.S. Pat. No. 5,561, entitled "Elective Controller".
No., 599, "Method of Optimal Controller."
Design of Multivariable Predictive C
U.S. Pat. No. 5,572,420 entitled "Control Utilizing Range Control,""Method of Optimal."
Scaling of Variables in a Multivaria
ble Predictive Controller Utilizing
No. 5,574,638, entitled "Range Control," all of which are commonly owned by the assignee of the present invention and incorporated herein by reference for all purposes. In the following, the aforementioned issued patents and US patent application Ser. No. 08/49, incorporated herein by reference, are incorporated herein by reference.
No. 0,499, collectively referred to as "Honeywell Patents and Applications").

[0007] A distributed control system used to monitor and control processes is a local control system.
Area network (LAN) architecture or wide area network (WA)
N) They are often connected by a common communication path such as an architecture. When the requesting node needs data from the responding node, it issues a request for data on the network, and the responding node then returns the data on the network. Many process control systems use supervisory control LANs or WANs integrated into one or more process control networks. The process control network contains the basic raw data required by the supervisory control network and other process control networks.

[0008] Typically, the supervisory controller is coupled to a flexible array of processor controllers using a communication driver that matches the particular processor controller being interfaced. The monitoring controller is a separate process controller or any client running by the monitoring controller.
They map the essential data of these process controllers to a similar database controlled by a supervisory controller for consistent storage and access by applications.

In general, the supervisory control network is configured to poll the process control network (s) at fixed or flexible intervals for all data mapped to the supervisory control system database by a user configuration. Yes). One or more server nodes physically couple the supervisory control local network and the wide area network to the process control network (s). These server nodes are data repositories for all client access between monitoring client nodes. However, problems arise when the amount of information in the process control network (s) is greater than all can be polled at an acceptable update rate. In such a case, two or more polls of the process control network are required to retrieve all the data required by the client application. This is especially true for client applications where the user switches back and forth between screens (views) displaying data from the process control network.

Accordingly, there is a need in the art for an improved supervisory control system that allows one or more client applications to more quickly access information in one or more process control systems. Especially in the art,
There is a need in the art for one or more client applications for an improved supervisory control system that provides faster data access, which can be achieved by periodic data polling.

SUMMARY OF THE INVENTION To address the shortcomings of the prior art described above, a robust, reliable, decisive,
It is a primary object of the present invention to provide a flexible data distribution or delivery scheme. As introduced above, a typical process facility includes many related processes, the various processes being associated with different stages of the overall process (
Processes such as refining, filtering, gas / oil separation and production of natural resources). The present invention introduces systems and methods that optimize the distribution of information and improve cooperation between peer-to-peer, client and server, and various other process facility controls.

In order to achieve this first object, the present invention controls related processes in a process facility and, in particular, efficiently distributes data between nodes of a real-time process control system controlling the facility. Systems and methods for Example process control systems include sensors, controllable devices, communication paths, and computer systems. The sensors and controllable devices are associated with various processes of the facility, and the communication path associates the sensors and controllable devices with a computer system. Computer·
The system operates on data associated with the process equipment and distributes the data among its nodes.

According to an advantageous embodiment, the node comprises both a client node and a process node, wherein the client node desires data relating to the equipment process, the process node controls the process, and thus the process node・ Control the data. The computer system includes a cache and a supervisory controller in addition to the associated nodes. A cache is a relatively fast memory device capable of storing multiple records. The monitoring controller is associated with the client node and the process node and may be distributed or centralized, and (i) controls the storage of a portion of the process data in the cache record; ii) Operate to selectively communicate a portion of such a record from the cache to the client node. The client node runs the client application and preferably interacts with the supervisory controller in a common way. The data stored in the cache record may be important data recently accessed by the client node.

Typically, the amount of information generated by a process is much greater than the amount from which it can be efficiently polled as a whole or at an acceptable update rate,
A cache provides a data repository that retrieves records therefrom in a relatively short time compared to polling one or more processes.

According to a related embodiment, a monitoring controller selectively communicates records in response to a request from a client node. In particular, the client node requests a particular subset of the process data, and the monitoring controller makes a determination as to whether the requested subset is stored in a cache. If the subset is stored therein, the supervisory controller communicates the subset to the client node; otherwise, it requests a copy from the process node.

In an alternative embodiment, the monitoring controller requests a copy of the subset from the process node at least substantially in parallel with determining whether the subset is stored in the cache. This embodiment is specific to the "latency" described above.
That is, a portion of the requested data subset is first searched in the cache, and then the current instance of the subset is requested from the process node when it is determined that the subset is not stored therein. Significantly eliminates unavoidable wait times when done. According to this embodiment, the supervisory controller makes requests to the processes associated with the cache, at least almost in parallel, avoids the above delays, shuts down when the subset is determined to be in the cache, Invalidate requests from the process nodes for selected instances of the subset at the time determined.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that those skilled in the art may better understand the detailed description of the invention that follows. Further features and advantages of the invention are described below, which form the subject of the claims of the invention. Those skilled in the art will readily appreciate that the disclosed concepts and particular embodiments can be used as a basis for adjusting or designing other configurations to carry out the same objects of the invention. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the broad aspects of the invention.

For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings. In the drawings, like numbers indicate like objects.

DETAILED DESCRIPTION The various embodiments used to describe the principles of the present invention in FIGS. 1-4, discussed below, and in this patent document, are for illustration purposes only. It should not be construed as limiting the scope. Those skilled in the art will appreciate that the principles of the present invention may be implemented in any suitably configured process equipment.

FIG. 1 is a configuration diagram of a process facility 100 in which a control system according to the principles of the present invention is mounted. An example process facility 100 processes raw materials and provides control center 1
05 and six related processes of items 110a-110f configured in three stages. As used herein, the term "comprising" means inclusive.
The example control center 105 typically includes a central area where operators (not shown) are located to monitor and control three example process steps. The first process stage includes three raw material crushers 110a-110c that receive a "feed" of raw material and turn the material into smaller particles of raw material, such as by using a mill or grinding wheel. The second process stage includes a washer 110d that receives the milled raw material and cleans it to remove residues from the first stage. The third process stage includes a set of sorters 110e and 110f that receive the milled and washed raw materials and separate it into the desired minerals and any remaining raw materials. This process equipment is provided for illustration, and the principles of such equipment are well known, so further discussion of this equipment is unnecessary beyond the scope of this patent document. .

The exemplary control system includes a supervisory controller 120 and six process nodes or process controllers 125 a-125 f, each implemented in software, and Honeywell AM K2LCN, AM K4LCN, AM H.
Appropriate existing computing resources such as MPU, AxM or similar systems
It can be performed by a system (stand-alone or network). Those skilled in the art will appreciate that these controllers can be implemented in hardware, software, firmware, or any suitable combination thereof. In general, the use of computing systems in control systems for process equipment is well known.

The monitoring controller 120 is directly or indirectly associated with each of the process controllers 125 to enable the exchange of information. As used herein, “associated with” and terms derived therefrom include, are interconnected, include, include, are connected to, are coupled to, are communicable with, and cooperate with. , Interleaving, being a property, being tied, having, having a property, and the like. The monitoring controller 120 may control the characteristics (state, temperature, pressure, flow, current, voltage, power, utilization, efficiency,
Cost and other economic factors) are monitored directly or indirectly through a process controller 125 associated with the process 110. Depending on the particular implementation, such monitoring may be an individual process, a group of processes, or an entire facility.

The monitoring controller 120 communicates with the associated process 110 via the process controller 125 and generates monitoring data to optimize the process equipment 100. As used herein, "monitoring data" controls, for example, a particular process, a group of processes, an entire facility, a process step, a group of steps, a process or sequence of steps, etc., to optimize the equipment as a whole Defined as a numerical, qualitative or other value generated by the monitoring controller 120 to perform (eg, direct, manage, coordinate, prompt, control, inspire, monitor, collaborate, etc.) . In a preferred embodiment, the monitoring data is generated dynamically and is based at least on the efficiency, production or economic cost of a given facility, and most preferably in all three factors.

The process controller 125 monitors the associated process 110 and operates to control the associated process in a manner that varies according to the monitoring data, and in particular coordinates one or more processes to monitor the monitored characteristic and overall. Improve facilities as. The relationship between the various parts of the monitoring controller 120 and the process controller 125 is:
Master-slave (complete compliance), coordination (compliance changes, such as by using monitoring data as a factor in controlling related processes),
Or either completely ignored (non-compliance). Depending on the particular implementation and the needs of a given facility, the relationship between the monitoring controller 120 and the particular process controller 125 may be static (ie, always one of compliance, collaboration, non-compliance) or dynamic (ie, Compliance or non-compliance ranges or narrower ranges over time) or switching between static and dynamic periods.

FIG. 1 depicts, by way of example only, process controllers 125 a-f as simple logic blocks coupled to processes 110 a-f. In practice, the process controllers 125a-f may be any of the process equipment 10 as a wide variety of equipment.
0 is implemented. In the simplest embodiment, the example process controller 125 is a micro-controller built on a circuit board.
controller), one of the controlled processes 110 (ie, the separator,
Washing machine, part of the crusher). In another embodiment, the example process controller 125 is separate from the controlled process 110 and is a personal computer (PC) coupled to the process 110 in a bus architecture.
) May be a stand-alone computer.

In a more complex embodiment, the example process controller 125 is a network node that is coupled to one or more processes 110 by a network architecture. The supervisory controller 120 then treats the network including the example process controller 125 and its associated process 110 as a single functional group. Finally, the example process controller 125 becomes a group of networked process controllers and their associated processes 110. The networked group is then treated by the monitoring controller 120 as a single functional group.

The process controllers 125a-f are used by the monitoring controller 120 for various purposes, including generating monitoring data and distributing process data to one or more client applications. Generate process data. Process data is also used by the process controller 125 to generate data to control the associated process 110. For example, the process controller 125 reads physical parameter data, such as temperature, pressure, and flow rate, from the process 110 and uses some or all of that process data, and possibly some of the monitoring data, to process the process 110. Control. This is especially true for feedback control processes.

The process data is transferred directly between the process controllers 125a-f in a peer-to-peer relationship as in a LAN network. For example, the process controller 4 that controls the washer (item 110d) includes a process controller 1 that controls the pulverizers 1 to 3 to determine the speed at which pulverized raw materials are output from the pulverizers 1 to 3. Request process data from ~ 3. The washer thereby adjusts the rate at which the crushed raw material is washed. For example, the washer reduces the amount of power used to clean the milled raw material when the amount of milled raw material sent to the washer is relatively small. The washer may "stand by" until the proper amount of comminuted raw material has accumulated, and then temporarily shut down to resume washing.

In some embodiments of the invention, supervisory controller 120 includes a LAN, a group of connected LANs, or a WAN architecture. One or more client applications run on nodes of the LAN / WAN architecture. The node is, for example, a personal computer (PC). The client application requests all of the same process and monitoring data to be transferred from the process controller at the same update rate. But,
A more likely scenario is that the client application is different,
In this scenario, a subset of potentially overlapping process and monitoring data is requested, and the process and monitoring data is required to be transferred to different client applications at different update rates.

To minimize overall data traffic and avoid bottlenecks in the heavily demanded process controller 125, a preferred embodiment of the present invention employs multiple requesting data from multiple nodes containing data. Implement a new scheme for distributing large amounts of cyclic data to nodes in a deterministic way. This means that data is transmitted from the node containing the data (ie, the issuer controller) to the node that needs the data (ie, the subscriber controller) without the need for the subscriber controller to repeatedly (cyclically) request the data. Is achieved by an issue / subscribe distribution scheme that allows The issuance and subscription scheme for distributing data is described in the joint application "Systems and Methods for Accessin."
g Data Using Cyclic Publish / Subscribe
US Patent Application entitled "e Scheme with Report By Exception" (patent attorney case no.
o. ) HWEL 01-00169), which is hereby incorporated by reference in its entirety.

Generally, the supervisory controller 120 polls at fixed or varying intervals all process data that is mapped by a user configuration into a database associated with the supervisory controller 120. Process controllers 125a-f. However, as described above, a problem arises when the amount of information in the process controller network (s) 125a-f is greater than the amount that can all be polled at one time at an acceptable update rate. In such a case, to retrieve all process data requested by the client application, one or more process
Two or more polls of the controllers 125a-f may be required. This is especially true for client applications that reciprocate by switching between screens (views) that display a relatively large amount of process data from a process control network where the process data frequently changes values.

To overcome this problem, the present invention provides a process controller 125a-f
Implements a high-speed dynamic cache associated with the supervisory controller 120 that transfers (updates) process data to the client application at a rate faster than the server can transfer process data. In the present invention, when the term "dynamic" is used in connection with a cache, it retains process and / or monitoring data that is currently or recently relevant to client applications communicating with the domain of the monitoring controller 120. Refers to the ability of the cache to The dynamic cache provides a more flexible mapping between the domain of supervisory control 120 and the domain of process controllers 125a-f.

In one embodiment of the invention, one or more server nodes physically couple monitoring controller 120 to process controllers 125a-f. These server nodes are data repositories for all client access between monitoring controller client nodes. Monitoring controller 125
Is a separate process controller 125a-f or monitoring controller 12
5 maps the essential process data of the process controllers 125a-f to a homogeneous database controlled by the monitor controller 125 for consistent storage and access by any client application executed by the client controller 5.

FIG. 2 illustrates a process control system 200 including a supervisory controller 120 including a dynamic cache 215 according to one embodiment of the present invention. Process control system 200 also includes a plurality of client nodes 201-203 that are coupled to monitoring controller 120. One or more client applications reside on each of the client nodes 201-203 and are executed by the client nodes along with the monitoring controller 120.

To simplify the following description of FIG. 2, the process controller 125 and its associated process (s) 110 will be referred to collectively as “process nodes”. The monitoring controller 120 is coupled to a plurality of process nodes 204-206. The monitoring controller 120 includes a driver interface layer 225 including a plurality of communication drivers 231 to 233. The communication drivers 231-233 are compatible with the corresponding nodes of the process nodes 204-206 and periodically or irregularly update process data from the process nodes 204-206 to update the dynamic cache 215. Used to search. The communication driver also handles writing a one-time request from the monitoring controller 120 to the process nodes 204-206, or reading a one-time request from the process nodes 204-206.

The monitoring controller 120 operates according to a common protocol such as an application programming interface (API).
Handles read / write of requests from 03. Client nodes 201 and 2
The 03 data access request is primarily retrieved or written from the dynamic cache 220, sometimes with a one-time service request to access less used process data in the process nodes 204-206.

When a client application requests process data, the request for data is sent to the supervisory controller 120 and received within the cache manager 220. In one embodiment of the present invention, cache manager 220 first searches dynamic cache 220 for the requested process data. If process data is found (cache hit), cache manager 220 forwards the process data to the requesting client application and the transaction ends. If no data is found (cache miss), the cache manager 220 returns to process node 2
Request process data from the appropriate one of 04-206. When the supervisory controller 120 receives process data from a process node, the cache manager 215 writes the process data to the dynamic cache 215 and sends the process data to the client application that originally requested it.
Transfer data.

In an alternative embodiment of the present invention, the cache manager 220
Upon receiving a request for process data from the application, the cache manager searches for the process data in the dynamic cache 215 almost simultaneously and issues the request for process data to the appropriate process node holding the process data. I do. When a cache hit occurs, the data request to the process node is canceled. When a cache miss occurs, the cache manager 220 waits for process data to be returned by the process node in response to a previously transmitted data request. Again, when process data is received from a process node after a cache miss, the process data is written to dynamic cache 215 and transferred to the client application that originally requested it.

The process data removes the oldest process data from the dynamic cache 215 each time it was last accessed to make room for new process data. Whenever the supervisory controller 120 retrieves the currently cached process data, the cache entry is time stamped to indicate the access time. It updates with new process data,
It is performed as a background activity by the cache manager 220 so that the foreground activity of processing client node data requests is not interrupted.

In a preferred embodiment of the present invention, supervisory controller 120 includes a plurality of server nodes including at least a first dynamic cache and a second dynamic cache. The second dynamic cache reflects the contents of the first dynamic cache, but data requests from client nodes 201-203 unless the first cache goes down and the second cache becomes the first cache. This avoids duplicating network traffic, since it does not actively access process data in response to the

To maximize the performance of the dynamic cache 215, only one copy of each process data is stored in the dynamic cache 215. Thus, even if multiple client applications request the same process data, all requests for that data will be sent to the dynamic cache 2
It is held in the same 15 entry positions. Client applications requesting less accessed data use the API to indicate that the process data request is a non-cyclical or less frequently used request. The supervisory controller 120 forwards the less accessed process data directly to the requesting client application, but does not add new entries after a cache miss because the process data request is relatively rare.

When data is written to a process node, the process data is transferred directly to the designated process node, but the cache manager 220 does not update the dynamic cache 215 based on the write operation. . Instead, the dynamic cache 215 is updated by reading the newly written process data back from the process node, so that the value in the dynamic cache 215 is always the same as the value in the process node. It is confirmed that.

FIG. 3 is a flowchart showing the initial configuration of the monitoring controller 120 and the subsequent routine operation. The supervisory controller 120 processes and
Poll nodes 204 to 206 and client nodes 201 to 203 (
Step 301), searching for user configuration data for each node (Step 3)
02). The monitoring controller 120 maps the requested process data based on the user configuration data and the subscription list of the client nodes 201 to 203 and the process nodes 204 to 206 to a similar database related to the monitoring controller 120 (step 303). Allocate one entry for one data, thereby avoiding duplicate copies of the same data requested by one or more client nodes and / or process nodes. afterwards,
During routine operation, the supervisory controller 120 repeatedly receives process data requests from the client application (step 304), particularly depending on how frequently the process data was requested and / or how recently the process data was requested. Then, the dynamic cache 215 is filled with at least a part of the process data retrieved from the process nodes 204 to 206 (step 305).

FIGS. 4A-4C are flowcharts illustrating the operation of the cache manager 220 and the dynamic cache 215 in more detail. The strategy for determining whether the requested process data is stored or not stored in the dynamic cache 215 is a “SUBSCRIPTION PERIOD” variable provided by the client node requesting the data, and a cache manager. 220 and two "data freshness" indicators "TIME-OF-LAST-UPDATE" and "T" maintained by the dynamic cache 215.
IME-OF-LAST-ACCESS ". TIME-OF-L
The AST-UPDATE value is a time stamp stored in the dynamic cache 215 associated with the process data, called DATUM X, where DATUM X was retrieved from the process controller 125 containing DATUM X. Shows the time. TIME-OF-LAST-ACCESS value is D
The time stored in the dynamic cache 215 associated with ATUM X
A stamp indicating the last time DATUM X was accessed in the dynamic cache 215 by any one of the client nodes 202-204.

At the beginning of a cache operation, the cache manager 220
A data request is received (step 401) and the SUBSCRIPTION PERIOD value specified by the requesting client node is read (step 402). If the SUBSCRIPTION PERIOD value is "0" (i.e., there is no value), the client node makes a "one-time" request for that data rather than a periodic request (or a subscription to the requested data). In that case, the cache manager 220 checks if the requested data is also in the dynamic cache 215 (step 411).

If the requested data is not cached, the cache manager 2
20 and the monitoring controller 120 use the one-time read function, rather than by subscribing to the requested data, to the appropriate process controller 125
The requested data is read from (step 412). Next, the retrieved data is placed in the dynamic cache 215 (step 413), and the TIME-OF
The LAST-UPDATE and TIME-OF-LAST-ACCESS values are updated in the dynamic cache 215 (step 414). The retrieved data is sent to the next requesting client node (step 415), and the cache manager 220 begins the next data request cycle (step 4).
01).

If the requested data is in the dynamic cache 215, the cache manager 220 returns the TIME-OF-LAST-UPDATE value and / or
Alternatively, verify that the data is still "fresh" by comparing the TIME-OF-LAST-ACCESS value to the configurable system-wide cache freshness time. If the data is still fresh, cache manager 220 reads the data from dynamic cache 215 and sends it to the client node requesting the data (step 417), and TIME-OF-LAST-AC.
The CESS value is updated (step 418). Next, the cache manager 220
Starts the next data request cycle (return to step 401).

If the data is not fresh, the cache manager 220 and the supervisory controller 120 retrieve the data requested by the appropriate process controller in a one-time read operation, place the retrieved data in the dynamic cache 215,
TIME-OF-LAST-UPDATE value and TIME-OF-LAST-AC
Update the CESS value and send it to the requesting client (step 41)
2-415).

If the SUBSCRIPTION PERIOD value is not a value of 0, the client node makes a circular (or periodic) request for data. However, the requested data is only subscribed if the rate (ie, frequency) of the repeatedly requested data is sufficient to subscribe to the requested data.
The cache manager 215 compares the SUBSCRIPTION PERIOD with the maximum configurable system-wide subscription period (step 404).

If the SUBSCRIPTION PERIOD exceeds the maximum, the data request is treated as a one-time request. Cache manager 220 determines whether the requested data is also in dynamic cache 215 at the same time. Once the requested data has been cached, a freshness check is performed, and if so, the data is retrieved from the dynamic cache 215 and sent to the requesting client, and the TIME-OF-LAST ACCESS value is updated (
Steps 416-418). If the requested data is not cached or stale, the cache manager 220 and monitor controller 120
Reads the requested data from the appropriate process controller 125 using a one-time read function, rather than subscribing to the requested data (step 412). The retrieved data is then placed in the dynamic cache 215 (step 413), and the TIME-OF-LAST-UPDATE value and the TIME-
The OF-LAST-ACCESS value is updated in the dynamic cache 215 (step 414). The retrieved data is sent to the next requesting client node (step 415), and the cache manager 220 begins the next data request cycle (return to step 401).

If the SUBSCRIPTION PERIOD is within the specified maximum, the requested data is cached in the dynamic cache 215. Cache manager 220 determines whether the requested data has already been subscribed (step 405). This is done by looking up the requested data in the dynamic cache 215 and determining whether the "Subscribed To" field (if found) associated with the data is set.

If the data has not been previously subscribed, the cache manager 220 and the supervisory controller 120 use the subscription mechanism to
(Step 431). The requested data is then read from the process controller 125 and the dynamic cache 21
5 and the “Subscribed To” field is set (
Step 432). The requested data is then forwarded to the requesting client node (step 433), and the TIME-OF-LAST-UPDATE value and T
The IME-OF-LAST-ACCESS value is updated in the dynamic cache 215 (step 434). Next, the cache manager 220 starts the next data request cycle (return to step 401).

If the data has been previously subscribed, the cache manager 220 reads the requested data from the dynamic cache (step 406) and
The ME-OF-LAST-ACCESS value is updated in the dynamic cache 215 (step 407). Next, the cache manager 220 starts the next data request cycle (return to step 401).

A first client node subscribes to the selected process data at a first subscription rate, eg, once a second, and a second client node
It also often occurs to subscribe to the same selected process data or a subset thereof at a second subscription rate, such as once per second. In this example, the terms "first" and "second" are used to distinguish client nodes from subscription rates, and do not imply a chronological order of occurrence. In a preferred embodiment of the present invention, the cache manager 220 retrieves process data from the process controller containing the data at a faster rate (once per second in this example). Cache manager 220 maintains both subscription rates in dynamic cache 215. Thereafter, if the first client node ceases subscribing to the selected process data, cache manager 220 returns to a lower subscription rate without action or intervention by the second client node (this example). Then once every two seconds).

If more than one client node subscribes to the same process data, cache manager 220 may process from the appropriate process controller at the fastest subscription rate specified by any subscribing client node.
Search for data. Thereafter, if the client node that subscribed at the fastest rate ceases to subscribe to the selected process data, the cache manager 220 will proceed to the second fastest subscribed without action or intervention by any subscribing client node. Return to speed.

While the invention and its advantages have been described in detail above, it will be understood by those skilled in the art that various modifications, substitutions, and substitutions can be made without departing from the broadest spirit and scope of the invention. Like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a process facility in which a control system according to the principles of the present invention is used.

FIG. 2 is a process control system including a supervisory controller including a dynamic cache according to one embodiment of the invention.

FIG. 3 is a flowchart showing an initial configuration of a monitoring controller and a subsequent routine operation.

4A-4C are flowcharts illustrating the operation of the cache manager and dynamic cache in more detail.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission Date] February 21, 2000 (2000.2.21)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Davis, Peter Shea, Australia, 2071, New South Wales, Sydney, Killara Panel Street, 27 (72) Inventor, Canavan, Ian Cay Australia, 5B045 AA05 DD12 GG02 JJ02 9A001 CC08 DD07 JJ01 JJ27 KZ54 5F 045 AA05 DD12 GG02 JJ02 9A001

Claims (28)

[Claims] 1. A system for distributing data between nodes of a process facility, wherein some of the nodes are client nodes that desire data related to the process, and some of the nodes are the client nodes. A process node for controlling process data, a cache having a relatively short time to retrieve a record; and a cache associated with the client node and the process node for storing a part of the process data in the record. A system including a supervisory controller that controls and selectively communicates a portion of the record from the cache to the client node. 2. The system of claim 1, wherein said supervisory controller selectively communicates said portion of said record in response to a request from said client node. 3. The system of claim 2, wherein the client node requests a subset of the process data, and wherein the supervisory controller determines whether the requested subset is stored in the cache. 4. The monitoring controller, in response to the determination, requesting an instance of a selected subset of the requested subset from the process node, or selecting an instance of the requested subset from the process node. 4. The system of claim 3, wherein either the request for is invalidated. 5. The system of claim 1, wherein the monitoring controller receives a subset of the process data from the process node and stores at least a portion of the subset in a record of the cache. 6. The system of claim 1, wherein the monitoring controller receives a subset of the process data from the process node and selectively communicates at least a portion of the subset to the client node. 7. The monitoring controller, the client node, and the process node are associated by a communication path having data traffic capability, and wherein the system is configured to efficiently utilize the data traffic capability. The system of claim 1, wherein the distribution of data is controlled using a monitoring controller. 8. A method of operating a system for distributing data between nodes of a process facility, wherein some of the nodes are client nodes that desire data related to the process, and some of the nodes are part of the nodes. Is a process node that controls the process data, wherein the method of operation uses a supervisory controller, is associated with the client node and the process node, and has a relatively short retrieval time in a cache record. Controlling storage of a portion of said process data; and selectively communicating a portion of said record from said cache to said client node. 9. The method of claim 8, wherein said step of selectively communicating is responsive to receiving a request from said client node. 10. The method of claim 9, wherein the client node requests a subset of the process data, and wherein the method further comprises determining whether the requested subset is stored in the cache. The described method. 11. In response to the determining step, further comprising: requesting an instance of a selected subset of the requested subsets from the process node; or selecting an instance of the requested subset from the process node. 11. The method of claim 10, comprising the step of invalidating the request for: 12. The monitoring controller further comprising: receiving a subset of the process data from the process node; and storing at least a portion of the subset in a record of the cache. The method described in. 13. The monitoring controller further comprising: receiving at the monitoring controller a subset of the process data from the process node; and selectively communicating at least a portion of the subset to the client node. Item 9. The method according to Item 8. 14. The method according to claim 14, wherein the supervisory controller, the client node, and the process node are associated by a communication path having data traffic capabilities, the method further comprising: The method of claim 8, further comprising utilizing the data traffic capability. 15. A supervisory controller for use in a system for distributing data among nodes of a process facility, wherein some of said nodes are client nodes that desire data related to the process. Some of the nodes are process nodes that control the process data, a memory that can be associated with a cache that has a relatively short time to retrieve a record, and that controls the storage of a portion of the process data in the record. A controller, which can be associated with the client node and the process node;
A communication controller for selectively communicating a portion of the record from the cache to the client node. 16. The monitoring controller according to claim 15, wherein said communication controller responds to a request from said client node. 17. The monitoring of claim 16, wherein the client node requests a subset of the process data and the memory controller determines whether the requested subset is stored in the cache. controller. 18. The communication controller, in response to the determination, requesting an instance of a selected subset of the requested subset from the process node, or selecting a selected instance of the requested subset from the process node. 18. The monitoring controller according to claim 17, wherein either the request for is invalidated. 19. The monitoring of claim 15, wherein the communication controller receives a subset of the process data from the process node and a memory controller stores at least a portion of the subset in a record of the cache. controller. 20. The monitoring controller of claim 15, wherein the communication controller receives a subset of the process data from the process node and selectively communicates at least a portion of the subset to the client node. 21. The monitoring controller, the client node, and the process node are associated by a communication path having data traffic capabilities, and the monitoring controller efficiently utilizes the data traffic capabilities to transmit data. The monitoring controller according to claim 15, which controls distribution. 22. A real-time process control system used to control a process facility, comprising: a plurality of sensors and a controllable device associated with a process of the process facility; A communication path for associating devices with a computer system, said computer system operating on data associated with said process equipment, distributing said data among nodes of said computer system, and a portion of said nodes. Are client nodes that desire data associated with the process, some of the nodes are process nodes that control the process data, and the computer system has a cache that has a relatively short time to retrieve records. And the client node and the process node Communicating with the control part of the storage of the process data, real-time process control system including a supervisory controller selectively communicating a portion of the recording from the cache to the client node in said recording. 23. The real-time process control system of claim 22, wherein said supervisory controller selectively communicates said portion of said record in response to a request from said client node. 24. The real time of claim 23, wherein the client node requests a subset of the process data and the supervisory controller determines whether the requested subset is stored in the cache. Process control system. 25. The monitoring controller, in response to the determination, requesting an instance of a selected subset of the requested subset from the process node, or selecting an instance of the requested subset from the process node. 26. The real-time process control system of claim 24, wherein either the request for is invalidated. 26. The real-time process control system of claim 22, wherein the supervisory controller receives a subset of the process data from the process node and stores at least a portion of the subset in a record of the cache. . 27. The real-time process of claim 22, wherein the monitoring controller receives the subset of the process data from the process node and selectively communicates at least a portion of the subset to the client node. Control system. 28. The supervisory controller, the client node, and the process node are associated by a communication path having data traffic capabilities and the supervisory controller for the system to efficiently utilize the data traffic capabilities. 23. The real-time process control system according to claim 22, wherein the distribution of data is controlled using: